Receiving detector for wireless telegraphy



May 26, 1925. 1,539,150

0. VON BRONK RECEIVING DETECTOR FOR WIRELESS TELEGRAPHY Filed Sept 3, 1921 hee/"t0? OTTO von I BRONK 85% his Patented May 26, 1925.

U ITED STATES ormo ,VON neon-K, on BERLIN, erinnnnw,

LOSE memearman M. ,B. n, colon o-r (GERMANX.

HALLESGHES, :01 BERLIN, GERMANY, :AJCOIRPORA- nnenrv ne mem Eon wrnnnnss mmemmy.

' Application filedfiepteniberg3, 19,21. S'erialNo. 49 ,454.

July 8, 192M), of; which theizillowing is a specification. p

In the art of wn'elessitelegraphy it: is, as is well known, very desirable for the re- 7 eeption oitelectrie oscillationsito admit these in iJQllG-fOrlIl, on the one hand, in-order to make possible a good diil'ei'entifation of' the reception iironi the atmospheric disturb- :the reception by detector.

'Variousprocesses means of ticker or sli pp'ing have become "known, for

receiving as tones the undaxnped oscillations which in themselves are vinaudlhle. lBut" most of the known arrangementsihave the disadvantage that even sliglht. fluctuations of the transmitting wave, or slight changes with auxiliary gi requencyythe to iewheehorf the Goldschuudt frequency changer, a fluca I change in- 'tuation of z-even 1% produces tone of about one octave.

The present invention renioyes this disadvantage by utlh'zing iwell lcnown prim cip'leiof electroteehnicsi ligan alternating current dynamo which, with direct-current excitation, would give the frequency N, is excited with the alternating.cunrent oi irequency nthen there wilhbe:obtaineditwo induced alternating potentials, nainely ,'N;+n and New. iForxthe present purpose a Inachine will be used which has a JiXed-and a rotating winding, inductively related to each other, and the machine can runysay,

with a "frequency of N:500 periods. With revolutions it must :therefore ha-ve, for instance, 20 poles. The pr mary windingot in: newer Mengn 3, 1921; 41 STAT. L, 1313;

" the-machine is now supplied with the received high frequency current .(ior instance '92:30000), .tliis-ivindi1ig forming, for, em ainpleya part ofthe antenna inductance. Infthe other winding there are then induced the two ftequeneiesn-FN and NO this secondary windingcan be connected to an aperiodic detector winding, with the ,result that the two-freqnencies get into inter- Y ferenc'ein the detector circuit and produce a tone equal to the dil'lerence quencies, i. e. 2'N '1000.

Inflthe drawings 'Fig. *1 "is a diagrammatic representation of such an arrangement by way of example. Figs. 2-andx3 illustrate ,re- =finen1ents,and Figs. 4 and 5 are modifica- =tions.

In Fig, -re iierence character 1. signifies the alternating current dynamo whose fixed winding 2 isconnected in the antenna 3, while the rotating winding 4 with the ,de tector '5- and the telephone 6" with the condenser '7 connected in parallel for ns the {detector-circuit r V The secondary circuit "will preferably not be made aperiodic, but, inj order to attain a maximum utilization of energy and loose coup'ling, the {two frequencies n+N and WA N,both of which are di fierent fronithe of their irereceiving wave, will he broughtout throiwh tunedfcircuits, by making, for instance, t 1e induced winding 4, shown in Fig. 2, form '21 part of the self-induetion ofa two-wave slightly damped circuitS and, which is coupled with the detector circuit '9, {5, 6, 7. The two-wave characteristic of circuit '8 is =parallel to aver-y small part of the self-induction-o'f the-circuitB, na1nely, to 001110, a

correspondingly large condenser 1 1 (socalled flywheel' condenser). In vthis manner diminution of the atniosp'herie disturbanees may be attained by theeircnit represented in Fig 3. 'is loosely coupled to tuned circuits :12 and 13,-onc each for the frequency no l-N; and n-N. By coupling these with the-common detector circuitle, 5, 6, 7', 15 then theeoupling sense of each halfo hthe detector cirattained, for instance, by connecting in The two =wave circuit 8 cuit can be chosen at will; for instance, the coil 1 f may be reversed with respect to coil 15, without any noticeable change in the reception, if the circuits l2 and 13 are sufficiently selective. But against atmospheric disturbances there will occur a weakening in the one position, because the disturbances, onaccount of their damped character, do not experience an exact division into two .new frequencies, so that a certain compensation takes place in the common detector circuit.

The secondary circuit 8 can, as is illus tratcd in Fig. l, be arranged so that it will react upon the primary circuit producing two further frequencies n-l-QN and n-QN. For this purpose the secondary circuit 8 is wound either as shortcircuited armature, or tuned to N-l-n and nN. By making the primary circuit three-waved by tuning it to n, 9'L-I-QN and n2N, then there are received the tones 2N and 4N. In principle, this effect is not different from the one previously described.

In all the described circuit arrangements the rotor-circuit at, as shown in Fig. 5, can be made aperiodic. This does not change anything in principle, but makes it possible to omit the troublesome sliding contacts.

Likewise, the new frequencies which are produced in thcillustrations can be secured through induction in the secondary circuit, through electric coupling (capacitive) by forming the machine 1 from a fixed and a rotating capacity, which influence each other periodically.

As the received tones are either equal to N or 2N or 4N etc., a frequency fluctuation of the sender does not change the tone at all and the tone is proportional to the number of revolutions of the receiving machine, that is, under normal conditions, the percentage variation will be small.

The machine can also be used for receiving tone transmitters so that the transmitted note is maintained. This is a great ad vantage of the apparatus, which is not present in any other of the usual methods of tone-reception of undamped oscillations. In this case the machine is allowed to run with a frequency which does not deviate too much from the number of sparks, but on the other hand deviates sufficiently that the beats between alternator frequency and spark frequency can no longer be discerned by the ear, i. e. amount to at least 20 per second. If the transmitter has the tone 1000 the ma chine will be run with frequencies of about 800 to' 980 and 1020 to 1200. This has the advantage that the number of revolutions can be fixed so that a foreign, disturbing tone-transmitter which has a different tone is greatly subdued, apparently, because in consequence of the rotation the secondary circuit is being periodically uncoupled from the antenna, so that a large part of the disturbances cannot enter into the secondary circuit.

Having described my invention, what I claim is:

1. The method of receiving electrical oscillations and minimizing interference due to aperiodic disturbances in which the rcceived signal currents are combined with a low frequency to aflect a common detector circuit comprising, combining the signal currents with the low frequency to produce two new high frequency currents, impressing said new high frequency currents, on the common detector circuit and selecting a sense of coupling with the detector circuit which minimizes the effect of aperiodic disturbances.

2. The method of receiving electrical oscillations in which the incoming high frequency oscillations are used for the excitation of an alternating current dynamo possessing a natural frequency of its own comprising heterodyning the frequencies obtained by the combining of the signal frequency oscillations and the natural fre-.

quency of the dynamo, to produce an audible beat.

3. The method of receiving electrical oscillations in which the incoming high frequency oscillations are used for the excitation of an alternating current generator possessing a natural frequency of its own which modulates the incoming frequency so as to produce new frequencies, comprising causing the new frequencies to interfere with each other so that a note of double the natural frequency of the generator is produced.

4. In combination, an alternating current generator, signal receiving means connected to the afield of said generator, a circuit connected to the armature of said generator, said circuit being arranged to resonate simultaneously the frequencies equal to the sum and difference of the signal frequency and natural generator frequency.

5. In combination, an alternating current generator, signal receiving means connected to the field of said generator, a circuit connected to the armature of said generator,

.said circuit being arranged to resonate simultaneously the frequencies equal to the sum and difference of the signal frequency and natural generator frequency and means for combining said resonance frequencies to produce a beat equal to a multiple of the natural generator frequency.

6. In combination, an alternating current generator, signal receiving means connected to the field of said generator, a circuit con nected to the armature of said generator, said circuit being arranged to resonate simultaneously the frequencies equal to the sum and difference of the signal frequency and natural generator frequency, interniedibeing arranged so that disturbing oscillaate circuits coupled to said armature circuit, tions received by the said receiving means one of said intermediate circuits being tuned oppose each other in their effect on said de- 10 to one of said resonance frequencies, the tector circuit. I other being tuned to the other resonance fre- In testimony whereof I aflix my signature. quency, a detector circuit coupled to said r intermediate circuits, the sense of coupling OTTO VON BRONX. i 

